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20790 has 64 divisors (see below), whose sum is σ = 69120. Its totient is φ = 4320.

The previous prime is 20789. The next prime is 20807. The reversal of 20790 is 9702.

20790 = T6 + T7 + ... + T49.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1885 + ... + 1895.

It is an arithmetic number, because the mean of its divisors is an integer number (1080).

220790 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20790, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34560).

20790 is an abundant number, since it is smaller than the sum of its proper divisors (48330).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20790 is a wasteful number, since it uses less digits than its factorization.

20790 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34 (or 28 counting only the distinct ones).

The product of its (nonzero) digits is 126, while the sum is 18.

The square root of 20790 is about 144.1873780884. The cubic root of 20790 is about 27.4969693630.

The spelling of 20790 in words is "twenty thousand, seven hundred ninety".